Automated test system and method for device having circuit and ground connections

ABSTRACT

An automated test system for testing a device includes a processor, a test apparatus, and a barrier circuit. The processor is operable to generate a control signal, said control signal including test parameters. The test apparatus comprises a first connection operable to be connected to a circuit connection of the device, a second connection operable to be connected to a ground connection of the device, and a third connection operable to be connected to a chassis of the device. The test apparatus is further operably connected to receive the control signal from the processor. The test apparatus is operable to perform a first test on the device based on the test parameters. The barrier circuit is operable to detect movement in the vicinity of the device. The barrier circuit is operably connected to cause the test apparatus to stop performing a first test on the device upon detection of movement in the vicinity of the device.

CROSS REFERENCE TO RELATED APPLICATION

Cross Reference is made to co-pending U.S. patent application Ser. No.09/183,214, filed Oct. 30, 1998.

FIELD OF THE INVENTION

The present invention relates generally to test systems and methods, andin particular, to test systems and methods used in testing deviceshaving circuit and ground connections for receiving power from externalsources.

BACKGROUND OF THE INVENTION

Devices that derive electrical power from external sources, such asutility power, typically include a circuit connection and a groundconnection for connecting to the external power source. Such devicesinclude, among other things, consumer appliances, industrial equipment,and computer equipment. The circuit connection in such devices generallyincludes two contact points across which the device is connected tocomplete the power circuit. The ground connection in the device isintended to be connected to an electrical ground. According to manyinternational safety standards, the ground connection must alsoelectrically connect the metal chassis of the device to electricalground.

Several international standards define tests relating to the electricalinterconnection and/or isolation of the circuit connection, the groundconnection, and the metal chassis of an electrical device. Such test arereferred to herein as electrical safety compliance tests. Two commonelectrical safety compliance tests are those generally referred to asthe dielectric withstand test, and the ground continuity test.Electrical devices must typically pass such tests before being soldcommercially.

The dielectric withstand test measures the isolation between the circuitconnection and the ground connection at high voltages. To this end, ahigh voltage typically exceeding 1000 volts AC or DC is applied acrossthe circuit connection and the ground connection of the device. Thecurrent is then measured. If the current exceeds a maximum allowablecurrent threshold, the isolation between circuit and ground connectionof the device is considered to be insufficient. If the isolation betweenthe circuit and ground connection is insufficient, high voltages maypropagate to the metal chassis during operation of the device, therebycreating a potential safety hazard.

The ground continuity test measures the resistance between the groundconnection and the device chassis. The ground continuity test assuresthat the metal chassis will be electrically grounded during normaloperation of the device. If a high resistance is detected, the chassismay not be properly grounded, thereby creating a potential shock hazard.

One problem associated with performing the dielectric withstand test andthe ground continuity test is that many countries have unique testrequirements. While the type of tests are generally the same fromcountry to country, the specific test parameters vary. For example, theU.S. standards body, UL, defines two alternative dielectric withstandtests. One UL dielectric withstand test requires that a product be ableto withstand application of 1500 volts AC for one minute. Another ULdielectric withstand test requires that a device be able to withstandapplication of 1725 volts DC for one second. By contrast, the UnitedKingdom standards body, BABT, requires that a device be able towithstand 2800 volts AC for one minute or 2125 volts DC for one second.Still other standards, such as the CSA standard of Canada, requiredevices to withstand other levels of voltage for particular timeincrements. Specific parameters associated with the ground continuitytest also vary among the different nations' standards.

Accordingly, in a manufacturing environment where different products areintended for export to different countries, testing a product forelectrical safety compliance requires a labor intensive procedure ofobtaining the applicable international standard, obtaining the testparameters associated with the applicable international standard, andperforming the test on the device using the appropriate test parameters.Moreover, the test data must be recorded and associated with the deviceunder test. Such activities are not only labor intensive, butfurthermore require highly skilled operators who are knowledgeable aboutthe products, their international markets, and the standards of variouscountries.

To assist in carrying out dielectric withstand tests and groundcontinuity tests, a dielectric tester known as the VITREK 944iDielectric Analyzer has been developed, which is available from VitrekCorporation of San Diego, Calif. The VITREK 944i Dielectric Analyzer(hereinafter “Vitrek Analyzer”) performs AC and DC dielectric tests,ground continuity tests and other tests, based on input test parameters.

To alleviate the need for providing test parameters for each operationof a test, the Vitrek Analyzer allows a user to store up to ninety-ninetest programs. To perform a particular test, the operator may select theappropriate one of the stored test programs through the keypad on theVitrek Analyzer.

The Vitrek Analyzer also includes the ability to communicate withexternal devices, such as a general purpose computer. As discussed inthe Vitrek 944i Dielectric Analyzer Operating and Maintenance Manual(Vitrek Corporation, 1994) (hereinafter “Vitrek Manual”), which isincorporated herein by reference, the Vitrek Analyzer allows individualtests to be configured and executed through an external communicationlink. In particular, the Vitrek Manual teaches that individual singlestep tests may be configured at a general purpose computer and thencommunicated to the Vitrek Analyzer. The Vitrek Manual also teaches thatthe Vitrek Analyzer may communicate test results over the communicationlink to an external device, such as general purpose computer.

While the Vitrek Analyzer provides a valuable tool for performingelectrical safety compliance tests, the Vitrek Analyzer nevertheless hasshortcomings. First, the user interface capabilities of the VitrekAnalyzer are limited. In particular, the stored test programs may onlybe accessed through the Vitrek Analyzer keypad by their two digitnumber. Thus, for example, if an operator stores several test programsin the Vitrek Analyzer, the operator must memorize or record on paperwhich test standard is associated with each stored test's two digitidentification number. Moreover, the test programs stored in the VitrekAnalyzer may not be accessed through the communication link, or in otherwords, by an external computer. Thus, if the test programs stored in theVitrek Analyzer are to be accessed, they must be accessed throughoperator input at the front panel of the Vitrek Analyzer, which, asdiscussed above, has extremely limited user interface capabilities.

Moreover, the Vitrek Manual does not teach a filly automated test systemthat is capable of performing tests that conform to the various nations'electrical safety compliance standards in an intuitive andstraightforward manner. There is a need, therefore, for a fullyautomated test system that performs one of a plurality of electricalsafety compliance tests with reduced labor effort and knowledge thanthat required by conventional test systems, including those taught bythe Vitrek Manual. There is a further need for such a fully automatedtest system that is menu-driven, thereby reducing the complexity ofoperation of the system. There is yet a further need for a system thatautomatically obtains tracking identification data associated with eachtest performed by the automated test system.

Another difficulty encountered in electrical safety compliance testingarises from the hazardous conditions that occur during such testing. Inparticular, dielectric withstand tests routine require application of ACor DC voltages well in excess of 1000 volts to the DUT. Such voltagescan be extremely hazardous to human beings. Accordingly, safetyprecautions must be taken to avoid inadvertent contact with a DUT whilea test is in progress. Such precautions may include isolating the DUT ina closed room or closed area. The use of a closed room or physicallyclosed off area can undesirably limit the location options of theelectrical safety compliance testing area within a manufacturingfacility. Moreover, use of such extensive physical barriers can beinconvenient to relocate.

There is an additional need, therefore, for providing safety precautionsin the high voltage testing environment of electrical safety compliancetesting that eliminates the need for large physical barriers.

SUMMARY OF THE INVENTION

The present invention fulfills the above needs, as well as others, byproviding a test system that and method that, among other things,incorporates a barrier circuit that detects movement in the vicinity ofa device under test and causes a test operation to stop upon detectionof such movement. By stopping test operations upon detection of movementin the vicinity of the DUT, the hazardous conditions inherent toelectrical safety compliance testing are removed any time a humanoperator approaches the DUT.

In one embodiment, the present invention is an automated test system fortesting a device having a circuit connection, a ground connection and achassis. The automated test system includes a processor, a testapparatus, and a barrier circuit. The processor is operable to generatea control signal, said control signal including test parameters. Thetest apparatus comprises a first connection operable to be connected tothe circuit connection of the device, a second connection operable to beconnected to the ground connection of the device, and a third connectionoperable to be connected to the chassis of the device. The testapparatus is further operably connected to receive the control signalfrom the processor. The test apparatus is operable to perform a firsttest on the device based on the test parameters. The barrier circuit isoperable to detect movement in the vicinity of the device. The barriercircuit is operably connected to cause the test apparatus to stopperforming a first test on the device upon detection of movement in thevicinity of the device.

The use of the barrier circuit in such an automated test system providesan automated test system that has the safety feature of shutting itselfdown when a human operator approaches the device under test. Moreover,the use of the barrier system described above eliminates the need for aseparate room or extensive physical barrier construction to protecthuman operators from the potentially hazardous testing operation.

The above features and advantages, as well as others, will become morereadily apparent to those of ordinary skill in the art by reference tothe following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary embodiment of an automated test systemaccording to the present invention;

FIG. 2 shows a representation of an exemplary user interface screen thatis used by the system in FIG. 1 to provide the operator with a pluralityof product model identifier from which to choose;

FIG. 3 shows an exemplary embodiment of a barrier circuit which may beemployed in the automated test system of FIG. 1;

FIG. 4 shows a flow diagram of the main operation of the processor ofthe automated test system of FIG. 1; and

FIG. 5 shows a flow diagram of the test operations of the processor ofthe automated test system of FIG. 1.

DETAILED DESCRIPTION

FIG. 1 shows an exemplary embodiment of an automated test system 10according to the present invention. The automated test system 10includes a storage device 12, a user interface 14, a processor 16, atest apparatus 18, a barrier circuit 20, a discharge circuit 22 and areceptacle box 24.

The storage device 12, the user interface 14 and the processor 16 arepreferably integrated into a general purpose computer 26. The generalpurpose computer 26 further includes input/output (“I/O”) circuitry 28that provides an interface between the general purpose computer 26 andvarious external devices, including, but not limited to, the testapparatus 18 and the discharge circuit 22. To this end, the I/Ocircuitry 28 may suitably be one or more circuit cards designed toprovide interface and/or communication circuitry that allow the generalpurpose computer 26 to communicate with the various external devices.Such devices are well known in the art. For example, in the embodimentdescribed herein, the I/O circuitry 28 includes a IEEE-488-PCII card forinterfacing to the test apparatus 18.

The storage memory 12 is one or more memory devices that are capable ofstoring data, and in particular, data identifying a plurality of sets oftest parameters. A test parameter is a value defining an aspect of atest. A set of test parameters is a group of one or more testparameters. Each of sets of test parameters is associated with one ormore of the products to be tested by the automated test system 10.

In accordance with the exemplary described herein, a set of testparameters includes the test parameters required for a dielectricwithstand test and a ground continuity test. Moreover, each set of testparameters preferably includes test parameters for the dielectricwithstand test and the ground continuity test as defined by a particularcertification body. Table 1 below shows three sets of test parametersthat may be stored in the memory 12 in an exemplary embodiment of thepresent invention. Table 1 further identifies the certification body towhich the test parameters in each set corresponds.

TABLE 1 BABT TUV UL Parameter Set 1 Set 2 Set 3 Dielectric WithstandTest AC voltage 2800 2100 1500 Duration of Application 60 sec 60 sec 60sec Maximum Current 40 ma 40 ma 40 ma Ground Continuity Test MaximumResistance 0.1 Ohms 0.5 Ohms 0.5 Ohms

It will be appreciated that a particular product could require some testparameters from one certifying body and some test parameters of anothercertifying body. Accordingly, a hybrid set of test parameters that isdefined by more than one certification body is possible. Moreover,certain product models may have unique product specific parameters thatdo not relate directly to a particular certifying body. In such a case,a set of test parameters would include those product-specific testparameters.

The storage device 12 is further operable to store a plurality ofproduct model identifiers that correspond to each of the product typesor models to be tested. Specifically, the automated test system 10 isintended for use in an environment in which several types of productsare required to be tested. Each product type or model is identified by aproduct model identifier.

Each of the product model identifiers is associated with at least one ofthe sets of test parameters. In other words, for each product type orproduct model that is to be tested by the automated test system 10, oneof the sets of test parameters will be applicable. In the exemplaryembodiment described herein, the set of test parameters associated witheach product model depends upon the country or countries in which theproduct type is intended to be sold. Thus, when the automated testsystem 10 is configured, each product type and the countries in which itis intended to be sold must be known.

For products intended for use in more than one country, the productmodel identifier is preferably associated with the set of testparameters that has the most stringent set of applicable testparameters. For example, if a product is intended for use in both theUnited Kingdom and the United States, its product model identifier asstored in the storage device 12 would be associated with the set of testparameters identified in Set 1 in Table 1. Set 1 consists of the BABTtest parameters, applicable in the United Kingdom, which are morestringent than the corresponding UL test parameters identified in Set 3in Table 1. The reason for using the most stringent set of applicableparameters is that the DUT need only pass the most stringent set of testparameters to obtain certification for all the countries in which it isintended to be sold.

In any event, to accomplish the above described storage functionality,the storage device 12 may suitably be any memory device ordinarilyemployed by general purpose computers and indeed may include a pluralityof devices including separate nonvolatile and/or volatile storagedevices, as is common in the art. It is noted that the storage device 12is also operable to store test results and user input information.

The user interface 14 further comprises an input device 30 and a displaymeans 32. The input device 30 may suitably be any combination of typicaluser input devices employed in general purpose computers. The inputdevice 30 is operable to receive, among other things, product modelidentifiers. To this end, the input device 30 may include a keyboard, amouse, a voice recognition system, or combinations of such devices thatallow an operator to provide data input to the general purpose computer26. The input device 30 may include, in addition to the elementsdescribed above, a bar code reading device and associated interfaceequipment. The inclusion of a bar code reading device may permitautomation of several of the user input steps discussed further below.

The display means 32 is any device that renders computer dataperceptible to a human operator. Such display means 32 may includecathode ray tubes, LCD displays, sound generation equipment and/orvariations and combinations thereof.

The processor 16 may suitably be any processor employed in a generalpurpose computer. Such processors are well known. The processor 16, thestorage device 12, the input device 30 and the display means 32 are alldirectly or indirectly interconnected through one or more digital bussesillustrated in FIG. 1 as the bus 35.

The processor 16 is operable to receive input from the input device 30,including input identifying a product model identifier. The processor 16is further operable to retrieve from the storage device 12 the set oftest parameters associated with the product model identifier. Theprocessor 16 is still further operable to generate a control signal thatincludes the retrieved set of test parameters, or at least informationrepresentative thereof.

The test apparatus 18 is a device operable to perform product testing byapplying an input to a DUT and measuring a quantity from the DUT. In theexemplary embodiment described herein, the test apparatus 18 is anelectrical safety compliance testing apparatus, such as the VitrekAnalyzer, that performs, among other things, dielectric withstand testsand ground continuity tests on DUTs. Preferably, the testing apparatus18 performs product testing by receiving, through an input, certain testparameters, including parameters specifying the inputs to be applied tothe DUT and acceptable threshold values of the measured quantities. Thetest apparatus 18 then applies the input and generates as output testresults, which may be pass/fail information, actual measurement data, orboth.

In addition, the test apparatus 18 in the preferred embodiment includesan automated safety circuit that stops testing operations when the testapparatus detects an unsafe condition. In particular, the test apparatus18 preferably shuts down test operations if a discontinuity is detectedbetween a ground connection of the DUT and a chassis connection of theDUT. Such a condition may indicate that the chassis of the DUT is notgrounded, which may be a serious safety hazard. Such automated safetycircuits are well known, and are included, for example, in the VitrekAnalyzer.

In any event, the test apparatus 18 is operably connected to receive thetest parameters from, and to provide test results data to, the processor16. To this end, the test apparatus 18 in the embodiment describedherein is coupled to the processor 16 through the I/O circuitry 28 andcommunicates with the processor 16 over a I.E.E.E. 488 link 17. It willbe appreciated, however, that the test apparatus 18 may be connected tothe processor 16 via other types of communication links.

The test apparatus 18 of FIG. 1 includes three test connections, a VHIconnection, a VLO connection, and a CH connection. The VHI and VLOconnections are provided to the receptacle box 24. The CH connection isprovided to the barrier circuit 20. The barrier circuit 20 includes atermination 34 that is normally electrically coupled to the CHconnection. The termination 34 is configured to be coupled to thechassis of a DUT, not shown. FIG. 3, discussed further below, shows theinterconnection of the CH connection, the barrier circuit 20, and a DUT44.

Referring again to FIG. 1, the receptacle box 24 is a device thatprovides a junction between the VHI and VLO connections and the circuitand ground connections, respectively, of the DUT. In particular, asdiscussed above, consumer and industrial devices typically have acircuit connection through which external power received. Likewise, suchdevices typically have a ground connection. In most devices, the circuitconnection constitutes two prongs of the power plug on the device andthe ground connection constitutes the third prong of the power plug.Thus, to facilitate interconnection to the DUT, the receptacle box 24includes one or more types of power plug receptacles adapted to receivestandard plug configurations.

The test apparatus 18 is coupled to the receptacle box 24 such that theVHI connection may be coupled to both circuit connections of the DUT,thereby shorting both circuit connections of the DUT, and such that theVLO connection is coupled to the ground connection of the DUT.

The discharge circuit 22 is a circuit that, among other things, isoperably connected to the processor 16 to receive a discharge controlsignal therefrom. The discharge circuit 22 is further operable to,responsive to the discharge control signal, provide a discharge pathbetween the circuit connections and ground connection of the DUT. Tothis end, the discharge circuit 22 includes a relay 36 having a coil 38and a contact 40. The contact 40 is connected at one end to the VHIconnection and at the other end through a shunt resistor 42 to the VLOconnection. The coil 38 is operably connected to the I/O circuitry 28 toreceive the discharge control signal from the processor 16. The shuntresistor 42 is preferably a 32 K ohm, 50 watt resistor. Such a resistorprovides a lower time constant for discharge than that provided bytypical discharge circuits within the test apparatus 18.

In a preferred embodiment, the relay 36 is a relay capable of carryingcurrent in excess of 1 amp. To this end, the relay 36 may suitably be a48 volt relay, wherein the coil 38 is further connected to a 48 voltpower supply, not shown, through the I/O circuitry 28. The use of such arelay and the associated 48 volt power supply allows for the heavy dutyoperation required to perform the discharge operation in a safe manner.

The barrier circuit 20 is a circuit that is operable to detect movementin the vicinity of the DUT, not shown, and then cause the test apparatus18 to stop performing a first test on the device upon detection ofmovement in the vicinity of the DUT.

In the exemplary embodiment described herein, the barrier circuit 20includes one or more devices that form an optical perimeter around alocation that includes the DUT. (See FIG. 3). The barrier circuit 20 isoperable to cause interruption of a safety compliance test performed bythe test apparatus 18 upon detecting movement of an object through theoptical perimeter. To this end, the barrier circuit 20 in the embodimentdescribed herein is connected between the CH connection of the testapparatus 18 and the chassis termination 34. The barrier circuit 20 isoperable to disconnect the CH connection from the chassis termination 34upon detection of the movement of an object through the opticalperimeter, which causes the test apparatus 18 to detect a groundcontinuity failure and consequently stop any test pursuant to theoperation of its automated safety circuits. More detail regarding thestructure and operation of the barrier circuit 20 is described furtherbelow in connection with FIG. 3.

In the general operation of the automated test system 10, the operatorordinarily first connects a DUT to the automated test system 10. To thisend, the operator couples the circuit and ground connections of the DUTto the receptacle box 24. In addition, the operator couples thetermination 34 to the chassis of the DUT.

The general purpose computer 26 then, through the display means 32,provides the operator with a plurality of product model identifiers fromwhich to choose for an upcoming test, wherein at least one of theproduct model identifiers corresponds to the DUT. The operator then,through the input device 30, selects the appropriate product modelidentifier and may further enter other information, such as a productserial number, operator name or the like.

The processor 16 then retrieves from the storage device 12 a set of testparameters associated with the product model identifier. As discussedabove, the set of test parameters preferably includes parameters for adielectric withstand test and a ground continuity test. Such testparameters are discussed in further detail below in connection withFIGS. 4 and 5.

Once the processor 16 retrieves the set of test parameters associatedwith the product model identifier, the processor 16 communicates the setof test parameters to the test apparatus 18. The test apparatus 18 thenexecutes the tests in accordance with the set of test parameters, andreports the test results to the processor 16. The test results maysuitably include pass/fail information, actual measurement data or both.The test results reporting capabilities of the test apparatus 18 mayvary for different types of test apparatus, but most should includeeither pass/fail information or actual test measurements. The VitrekAnalyzer is operable to provide both types of test results. Theprocessor 16 may in any event create a data file using the test resultsand any other relevant information, such as, for example, the productidentification or serial number.

The processor 16 then, upon completion of the test, provides a dischargecontrol signal to the discharge circuit 22, and in particular, to thecoil 38 of the relay 36. Upon receiving the discharge control signal,the discharge circuit 22 causes immediate dissipation of any residualcharge on the DUT. To this end, the discharge control signal energizesthe coil 38, which, in turn, causes the contact 40 to close. When thecontact 40 is closed, the VHI connection, which is connected to thecircuit connection of the DUT, is shunted to the VLO connection, whichis connected to the ground connection of the DUT, through the shuntresistor 42. The residual charge within the DUT then dissipates throughthe shunt resistor 42.

It is noted that the processor 16 is also programmed to cause operationof the discharge circuit 22 any time the test apparatus 18 stops a testoperation, and not just upon successful completion of a test. Thus, forexample, if the test apparatus 18 stops operations because of adetection of a breach of the optical perimeter by the barrier circuit20, then the processor 16, which receives a signal from the testapparatus 18 indicating the stop of test operations, causes thedischarge circuit 22 to dissipate the charge on the DUT.

In any event, the automated test system of the present invention thusprovides an intuitive, easy to use test system for electrical safetycompliance testing. In contrast to prior art systems, an operator usingthe present invention need not know the specific test parametersprescribed by the various international certifying bodies such as UL,CSA, BABT and others. In addition, the operator need not even know thecountries in which certain products are intended to be sold.Accordingly, the present invention potentially reduces the training,labor and operational costs of electrical safety compliance testing.Moreover, the present invention further automates the test reportingprocess by employing the general purpose computer to generate datarecords including test results and other DUT and/or operatoridentification information.

Another advantage of the present invention is the safety and efficiencyenhancements provided by the discharge circuit 22, described above. Thedischarge circuit 22 provides an automated discharge device that reducesthe time required to discharge a DUT after being subjected to a highvoltage test. Although test apparatus such as the Vitrek Analyzer willeventually dissipate residual charge on a DUT after a high voltage test,such dissipation is relatively slow. The present invention, by providinga relay and shunt resistor, can dissipate high residual charges quicklyand safely. The reduced discharge time not only improves throughput, butalso diminishes the likelihood that a human operator will contact ahazardously charged DUT.

Yet other advantages of the present invention are provided by thebarrier circuit 20. As described above, the barrier circuit 20 isoperable to stop operations of the automated test system 10 if movementis detected in the vicinity of the DUT. The barrier circuit 20 thusfurther enhances the safety of the operation of the automated testsystem. Moreover, the combination of the barrier circuit 20 and thedischarge circuit 22 provide still further protection by automaticallydischarging a DUT upon movement of an object in the vicinity of the DUT.

FIG. 3 shows the an exemplary embodiment of the barrier circuit 20according to the present invention. Also shown for contextual purposesin FIG. 3 is an exemplary DUT 44 and the receptacle box 24 from FIG. 1connected for the automated performance of a dielectric withstand testand a ground continuity test. The exemplary barrier circuit 20 describedherein includes an optical transceiver 46, a plurality of mirrors 48, 50and 52, and a relay circuit 54.

The optical transceiver 46 is a device operable to transmit light oroptical beams, and preferably infrared optical beams, and detect thereception of the same optical beam. The optical transceiver 46 isoperable to generate at least one output signal, referred to herein as adetection signal, indicative of whether it is receiving the transmittedoptical beam.

In the preferred embodiment, one or more such optical transceivers 46generate a plurality of substantially vertically aligned beams to froman optical “fence”. To this end, the optical transceiver 46 may suitablycomprise a model P-4148B-2A-L1-15X-5R transmitter/receiver availablefrom Scientific Technology, Inc. of Hayward Calif. The ScientificTechnology, Inc. transmitter/receiver generates several verticallyspaced optical beams and is operable to provide a detection signalindicating whether it is receiving all of the transmitted beams.Alternatively, one or more transceivers that transmit and detectreception of a single beam may be used as the optical transceiver 46. Inaddition, the use of an integrated transmitter/receiver is given by wayof example, and those of ordinary skill in the art may readily employone or more separate optical transmitters and optical receivers toperform the functions ascribed to the optical transceiver 46.

The plurality of mirrors 48, 50 and 52 are advantageously configured toreflect one or more optical beams transmitted by the optical transceiver46 in a polygonal path to be received by the optical transceiver 46. Theresulting polygonal path defines an optical perimeter 56 around alocation that includes the DUT 44.

The relay circuit 54 preferably includes a first ground interrupt relay58 comprising a coil 60 and a double pole, double throw switch contact62. The coil 60 is operably connected to receive a signal indicating thestatus of the optical perimeter 56 from the transceiver 46. The statusof the optical perimeter 56 is determined by whether the transceiver 46is receiving all of the transmitted optical beams. When the transceiver46 receives all of the transmitted optical beams, or in other words, theoptical perimeter is intact, then the transceiver 46 provides adetection signal to the coil 60 that causes the switch contact 62 to beclosed. Otherwise, when the transceiver 46 does not receive all of thetransmitted optical beams, or in other words, if an object is breachingthe optical perimeter 56, then the transreceiver 46 provides a detectionsignal to the coil 60 that causes the switch contact 62 to be open.

To this end, the switch contact 62 is connected to alternatively connectand disconnect the CH connection from the test apparatus 18 of FIG. 1 tothe termination 34. The termination 34 is connected to the chassis ofthe DUT 44.

In the exemplary embodiment described herein, the relay circuit 54further includes a second or redundant ground interrupt relay 64. Thesecond ground interrupt relay 64 has the same structure and operation asthe first ground interrupt relay 58 and provides redundancy of operationin case of a failure of the first ground interrupt relay 58.

In operation, the optical transceiver 46 transmits one or more opticalor light beams and monitors for reception of the beams. The plurality ofmirrors 48, 50 and 52 reflect the one or more light beams in a polygonalpath around the DUT 44 such that the polygonal path terminates at thetransceiver 46, thereby forming the optical perimeter 56 around the DUT44. As long as nothing breaches the optical perimeter 56, thetransceiver 46 receives all the transmitted light beams and provides adetection signal indicative thereof to the first and second groundcontinuity relays 58 and 64. That signal causes the switch contact 62and the corresponding switch contact of the second ground continuityrelay 64 to be closed.

Because the switch contacts of the ground continuity relays 58 and 64are closed, the CH connection is electrically shorted to, or coupled tothe chassis of the DUT 44. Under such conditions, the test apparatus 18of FIG. 1 will perform the tests described above in connection with FIG.1.

In particular, as discussed above, the test apparatus 18 has automatedsafety circuits that monitor for unsafe conditions, and in particular,for discontinuity between the ground connection and the chassis of theDUT 44. The test apparatus 18 monitors for discontinuity by measuringthe resistance between the CH connection and the VLO connection. Thus,as long as the CH connection is shorted to the chassis of the DUT 44 andthe chassis is internally coupled to the ground connection, the testapparatus 18 can start and continue test operations on the DUT 44.Accordingly, two conditions must be present for the test apparatus toperform tests: the DUT 44 must have at least some continuity between itsground connection and chassis; and the optical perimeter 56 must beintact and uncompromised.

If an object, for example, a person, breaches the optical perimeter 56,the transceiver 46 does not receive all the transmitted optical beams.When the transceiver 46 does not receive all the light beams, thetransceiver provides a detection signal to the ground continuity relays58 and 64 that cause them to disconnect the CH connection from thetermination 34. As a result, the test apparatus 18 (FIG. 1) will detecta discontinuity from the CH connection to the VLO connection, and stopany testing (or prevent a new test) because of the detecteddiscontinuity.

As a result, the barrier circuit 20 exploits the primitive automatedsafety capabilities of the test apparatus 18 by effectively “mimicking”a ground continuity failure when the optical perimeter 56 is breached.In particular, the barrier circuit 20 uses the relay 58 in the groundcontinuity circuit to cause the test apparatus 18 to detect a groundcontinuity failure when the optical perimeter 56 is compromised. The useof this inherent safety feature of the test apparatus for the unintendedfunctionality described herein enables the barrier circuit 20 to beinexpensively and efficiently implemented.

Central to the automation features of the automated test system of thepresent invention is the operation of the processor 16 of FIG. 1. FIGS.4 and 5 show exemplary flow diagrams of the operations of the processor16 of FIG. 1 in carrying out a electrical safety compliance testaccording to the present invention. Specifically, FIG. 4 shows a flowdiagram 100 of the main level program carried out by the processor 16and FIG. 5 shows a flow diagram 200 of the operations carried out by theprocessor 16 in performing the “execute test” routine, or step 125 ofthe flow diagram 100 of FIG. 4. The operations shown in FIGS. 4 and 5will be discussed with an ongoing reference to the elements shown inFIG. 1.

Referring to FIG. 4, the processor 16 in step 105 obtains inputidentifying the operator, such as, for example the operator's name. Theoperator's name may be required as part of the reporting or recordkeeping requirements of the relevant certifying agency. The processor 16obtains the operator's identification and stores it in the storagedevice 12 for further use in step 135, discussed further below. Aftercompletion of step 105, the processor executes step 110.

In step 110, the processor 16 causes the display means 32 to display aplurality of product model identifiers and a prompt for the operator toselect one of the product model identifiers. In the embodiment describedherein, the product model identifiers are presented in a “menu” format.The product model identifiers are typically product model numbers orproduct names. For example, as shown in the exemplary display means menuof FIG. 2, the product model identifiers may suitably be “DEFINITY BCS”,“DEFINITY GWS”, “DEFINITY INTW” and “DEFINITY G1_MED.

Thereafter, in step 115, the processor 16 receives input from the inputdevice identifying the appropriate product model identifier. To thisend, the operator will have ascertained which of the product modelidentifiers describes the current DUT.

If a DUT is a product model for which the appropriate product modelidentifier is not displayed in step 110, then the operator may not beable to test the DUT using the automated test system 10 withoutmodifying the automated test system 10. In particular, the data in thestorage memory 12 would have to be modified to accommodate the newproduct model. In normal operation, however, the product modelidentifier will be displayed in step 110 and the operator will be ableto select an appropriate product model identifier from the list in step115.

In an alternative embodiment, step 110 may be reconfigured to provide tooperator with a selection of international standards, such as UL, CSA,BABT or the like, instead of product model identifiers. The operatorwould then select the appropriate country for the DUT in step 115. Whilesuch an alternative would encompass some of the advantages of thepresent invention, it nevertheless requires a higher level of knowledgeabout the product, and in particular, the countries in which it will besold. Moreover, some knowledge of the testing standards of severalcountries would need to be known such that the operator may select thestandard with the most stringent standards. Thus, while providing anoperator with a selection of international standards (or country names)provides some of the automation advantages of the present invention, itdoes not provide the same level of simplicity as the preferredembodiment of steps 110 and 115 described above.

In any event, once the product model identifier is selected in step 115,the processor 18 then in step 120 obtains a product identificationassociated with the DUT. The product identification number is preferablya unique product identification number or alphanumeric string. Unlikethe product model identifier wherein each product model identifierdescribes a type of product, the product identification is associatewith a single product or device. To obtain the product identification,the input device 30 may include bar code scanning equipment to scan abar code label on the DUT. In any event, the processor 18 then storesthe product identification in the storage memory 12 for use in step 135,discussed further below.

It is noted, however, that in some cases, the product identification orserial number may inherently include a product model identifier. In sucha case, steps 110 and 115 would not be necessary because the productmodel identifier would be provided in step 120.

After step 120, the processor 16 executes the test routine, representedin FIG. 4 as step 125. In general, the processor 16 causes the testapparatus 18 to perform one or more tests in accordance with a set oftest parameters associated with the selected product model identifier.The processor 16 then receives the test results from the test apparatus.The test results may simply include pass/fail information, actualmeasurement results, or both. Further detail of the “execute test”routine of step 125 is provided in the flow diagram 200 of FIG. 5,discussed further below.

One the test has been executed, the processor 16 then executes step 130.In step 130, the processor 16 causes the display means 32 to display atleast some indication of the test results received from the testapparatus 18 in step 125. The display of the test results providesfeedback to the human operator so that the human operator mayappropriately route the DUT based on the test results.

The processor 16 thereafter in step 135 formulates a data record usingthe test results and other data relating to the DUT. The data recordpreferably includes at least some of the test results, the productidentification, and the operator identification. To this end, theprocessor 16 uses the test results provided by the test apparatus 18 instep 125, and retrieves from the storage device 12 the productidentification and the operator identification. The resulting datarecord may then be stored or uploaded to a remote data base forsubsequent reporting to the appropriate certification body and/or forgeneral documentation of the test procedure.

Referring now to FIG. 5, step 125 is shown in detail as the flow diagram200. In step 205, the processor 16 communicates a first subset of testparameters to the test apparatus 18. The first subset of test parametersare the test parameters for the ground continuity test. The main testparameters of the ground continuity test include the duration of thetest and the maximum allowable resistance measured between the groundconnection of the DUT and the chassis. The appropriate values for theseparameters depend on the governing standard, for example, UL, CSA orBABT, and would be known or readily ascertainable by those of ordinaryskill in the art. Communication of those parameters to the testapparatus 18 would be known to those of ordinary skill in the art. Inthe exemplary embodiment described herein wherein the test apparatus 18is the Vitrek Analyzer, instructions for programming the processor 16 toconfigure the Vitrek Analyzer to perform ground continuity tests inaccordance with specific test parameters through remote communicationsare provided on page 16 of the Vitrek Manual.

Once the processor 16 has communicated the first subset of testparameters to the test apparatus 18 in step 205, the processor 16 instep 210 provides a start test command to the test apparatus 18. Thetest apparatus 18 subsequently performs the ground continuity test inaccordance with the first subset of test parameters and returns testresults in the form of a pass/fail signal to the processor 16.

In step 215, the processor 16 determines whether it has received a passor fail indication from the test apparatus 18. If the processor 16determines that it has received a pass indication, it proceeds to step220 to proceed with the dielectric withstand test. If, however, theprocessor determines that it has received a fail indication, then theprocessor proceeds to step 235.

In step 235, the processor 16 requests and receives additional testresults in the form of actual test measurement values from the testapparatus 18. Thus, for example, if the ground continuity test failed,then the processor in step 235 obtains the measured resistance betweenthe ground connection of the DUT and the chassis of the DUT forsubsequent recording and analysis. After receiving the additional testresults in step 235, the processor 16 in step 240 provides a signal tothe discharge circuit 22 that causes the discharge circuit to dissipateany residual charge off of the DUT in the manner described above inconnection with FIG. 1. After step 240, the test is terminated and theprocessor 16 proceeds as described above in connection with FIG. 4.

As evidenced above, if the DUT fails the ground continuity test, theprocessor 16 does not continue with the dielectric withstand test, butinstead continues with the display and data record creation operations(steps 130 and 135) of FIG. 4. The reason that the processor 16 does notcontinue with the dielectric withstand test is that the failure of theground continuity test can render the dielectric withstand test, whichtypically involves high and dangerous voltages, extremely hazardous.

Referring again to step 215, it is noted above that if the processor 16determines that it has received a pass indication from the testapparatus 18 in connection with the ground continuity test, theprocessor 16 executes 220. In step 220, the processor 16 communicates asecond subset of test parameters to the test apparatus 18. The secondset of test parameters include the parameters for the dielectricwithstand test. The main parameters of a dielectric withstand testinclude the type of voltage applied to the DUT, the quantity of voltageapplied, the duration of the applied voltage, and the maximum allowableleakage current measured from the circuit connection to the groundconnection of the DUT. Additional parameters for this test areidentified in pages 43 and 44 of the Vitrek Manual. As with the groundcontinuity test, the values of the dielectric withstand test parametersfor the various certifying agencies would be known to, or readilyascertainable by, those of ordinary skill in the art.

Once the processor 16 has communicated the second subset of testparameters to the test apparatus 18 in step 220, the processor 16 instep 225 provides a start test command to the test apparatus 18. Thetest apparatus 18 subsequently performs the dielectric withstand test inaccordance with the second subset of parameters and returns test resultsin the form of a pass/fail signal to the processor 16. In performance ofa dielectric withstand test, the test apparatus 18 applies a highvoltage (defined by the test parameters) across the circuit connectionand ground connection of the DUT through the VHI and VLO connections.The test apparatus 18 then measures the current flow from the circuitconnection and ground connection to determine whether the isolation ofthe ground connection is sufficient.

In step 230, the processor 16 determines whether it has received a passor fail indication from the test apparatus 18. If the processor 16determines that it has received a pass indication, it proceeds directlyto step 240 to proceed with providing the discharge control signal tothe discharge circuit 22 to dissipate the residual charge on the DUT.If, however, the processor 16 determines that it has received a failindication, then the processor proceeds first to step 235 to obtainadditional test results including the actual test measurements.Thereafter, the processor 16 proceeds to step 240 and proceedsaccordingly.

It will be noted that the embodiments described above are merelyexemplary, and that those of ordinary skill in the art may readilydevise their own implementations that incorporate the principles of thepresent invention and fall within the spirit and scope thereof.

For example, the use of an optical perimeter in the barrier circuit 20is given by way of example only. At least some of the advantages of thepresent invention may be accomplished by other devices that detectmovement or proximity of people near the DUT. Such devices may suitablyreplace the optical transceiver 46 and mirrors of the barrier circuit 20disclosed herein. Moreover, the relay circuit 54 may suitably bereplaced by other control devices that cause the test apparatus 18 tostop operating upon receipt of a detection signal indicating that theoptical perimeter has been breached. In one alternative embodiment, thecontrol device may suitably be the processor 16. In such a case, theoptical transceiver 46 would provide the detection signal to theprocessor 16 through the I/O circuitry 28 and the processor 16 wouldprovide control signals to the test apparatus 18 causing it to stopoperations if the detection signal indicates that the optical perimeter56 has been compromised.

We claim:
 1. A method of disabling operation of a test apparatusresponsive to motion in proximity to a first location, wherein theoperation of the test apparatus causes hazardous conditions in the firstlocation, the method comprising: a) forming an optical perimeter aroundthe first location; b) causing operation of the test apparatus under thecontrol of a processor, the test apparatus at least partially creating ahazardous condition in the first location by applying a voltageexceeding 1000 volts to a device located within the first location; c)detecting movement of an object through the optical perimeter; d)providing a detection signal to a control device upon detection ofmovement of an object through the optical perimeter; and e) causing thetest apparatus to stop operating responsive to the control devicereceiving the detection signal by removing the voltage from the device.2. The method of claim 1 wherein step a) further comprises: using anoptical transmitter to transmit a light beam in a first direction;reflecting the light beam in a plurality of directions such that thefirst direction and the plurality of directions together define theoptical perimeter; and using an optical receiver located proximate theoptical transmitter to receive the light beam.
 3. The method of claim 2wherein step c) further comprises detecting a failure by the opticalreceiver to receive the light beam.
 4. The method of claim 1 whereinstep a) further comprises: using an optical transmitter to transmit aninfrared light beam in a first direction; reflecting the infrared lightbeam in a plurality of directions such that the first direction and theplurality of directions together define the optical perimeter; and usingan optical receiver located proximate the optical transmitter to receivethe infrared light beam.
 5. The method of claim 1 wherein step a)further comprises forming an optical perimeter comprising a plurality ofsingle light beam perimeters, each single light beam perimeterassociated with a single transmitted light beam.
 6. The method of claim5 wherein step a) further comprises forming at least one of theplurality of single light beam perimeters by: using an opticaltransmitter to transmit a light beam in a first direction; reflectingthe light beam in a plurality of directions such that the firstdirection and the plurality of directions together define the singlelight beam perimeter; and using an optical receiver located proximatethe optical transmitter to receive the light beam.
 7. An automated testsystem for testing a device, the device having a circuit connection, aground connection and a chassis, the automated test system comprising: aprocessor operable to generate a control signal, said control signalincluding test parameters; a test apparatus comprising a firstconnection operable to be connected to the circuit connection of thedevice, a second connection operable to be connected to the groundconnection of the device, and a third connection operable to beconnected to the chassis of the device, the test apparatus furtheroperably connected to receive the control signal from the processor, thetest apparatus operable to perform a first test on the device based onthe test parameters; a barrier circuit operable to detect movement inthe vicinity of the device, the barrier circuit operably connected tocause the test apparatus to stop performing a first test on the deviceupon detection of movement in the vicinity of the device.
 8. The systemof claim 7 wherein the barrier circuit comprises: an optical transmitteroperable to generate a light beam; an optical receiver operable toreceive a light beam and generate a detection signal indicative ofwhether the optical receiver is receiving the light beam; a plurality ofreflecting devices configured to reflect a light beam generated by theoptical transmitter to the optical receiver in a path that defines aperimeter around the first location; and a control device operablyconnected to the optical receiver to obtain the reception signal, saidcontrol device further operable to cause the test apparatus to stopoperating when said detection signal indicates that the optical receiveris not receiving the light beam.
 9. The system of claim 8 wherein thecontrol device comprises the processor and wherein the processor isoperably coupled to receive the detection signal, and wherein theprocessor is further operable to provide a control signal to cause thetest apparatus to stop operating when the detection signal indicatesthat the optical receiver is not receiving the light beam.
 10. Thesystem of claim 8 wherein the control device includes a switching deviceoperably coupled to the test apparatus to cause the test apparatus tostop operating when the detection signal indicates that the opticalreceiver is not receiving the light beam.
 11. The system of claim 10wherein the switching device comprises at least one relay.
 12. Thesystem of claim 10 wherein the switching device comprises a first relayand a second relay, each relay separately operable to cause the testapparatus to stop operating when the detection signal indicates that theoptical receiver is not receiving the light beam.
 13. The system ofclaim 10 wherein the test apparatus includes an automatic safety featurein which the test apparatus stops operating upon a detection of adiscontinuity between a first connection and a second connection of thetest apparatus, and wherein the switching device is operably coupledbetween the first connection and the second connection; and theswitching device closes responsive to receiving the reception signalwhen the reception signal indicates that the optical receiver isreceiving the light beam and opens responsive to receiving the receptionsignal when the reception signal indicates that the optical receiver isnot receiving the light beam.
 14. A method of disabling operation of atest apparatus responsive to motion in proximity to a first location,wherein the operation of the test apparatus causes hazardous conditionsin the first location, the method comprising: a) forming an opticalperimeter around the first location; b) causing operation of the testapparatus under the control of a processor, the operation of the testapparatus including performing one or more electrical safety compliancetests on a device located within the first location; c) detectingmovement of an object through the optical perimeter; d) providing adetection signal to a control device upon detection of movement of anobject through the optical perimeter; and e) causing the test apparatusto stop operating responsive to the control device receiving thedetection signal.
 15. The method of claim 14 wherein: step b) furthercomprises causing the test apparatus to apply a voltage exceeding 1000volts to the device.
 16. The method of claim 14 wherein step a) furthercomprises: using an optical transmitter to transmit an infrared lightbeam in a first direction; reflecting the infrared light beam in aplurality of directions such that the first direction and the pluralityof directions together define the optical perimeter; and using anoptical receiver located proximate the optical transmitter to receivethe infrared light beam.
 17. The method of claim 14 wherein step a)further comprises: using an optical transmitter to transmit a light beamin a first direction; reflecting the light beam in a plurality ofdirections such that the first direction and the plurality of directionstogether define the optical perimeter; and using an optical receiverlocated proximate the optical transmitter to receive the light beam. 18.The method of claim 17 wherein step c) further comprises detecting afailure by the optical receiver to receive the light beam.
 19. Themethod of claim 14 wherein step a) further comprises forming an opticalperimeter comprising a plurality of single light beam perimeters, eachsingle light beam perimeter associated with a single transmitted lightbeam.
 20. The method of claim 19 wherein step a) further comprisesforming at least one of the plurality of single light beam perimetersby: using an optical transmitter to transmit a light beam in a firstdirection; reflecting the light beam in a plurality of directions suchthat the first direction and the plurality of directions together definethe single light beam perimeter; and using an optical receiver locatedproximate the optical transmitter to receive the light beam.